Jonathan Girven
I have recently successfully completed a PhD in the Astronomy and Astrophysics group at the University of Warwick. My supervisors were Dr Danny Steeghs and Prof Boris Gänsicke.
Summary:
My thesis is entitled "Degenerate Objects in Digital Sky Surveys". I have had a particular focus on hydrogen-rich atmosphere (DA) white dwarf stars in the Sloan Digital Sky Survey (SDSS). However, I have devoted some of my time to other degenerate type objects such as subdwarf stars and to a host of other large scale sky surveys including GALEX, CMC, 2MASS and UKIDSS. I am experienced in looking for average properties and correlations in large samples, as well as searching for outliers. For example, my publication on "DA white dwarfs in SDSS Data Release 7 and a search for infrared excess emission" started with the entire SDSS database (hundreds of millions of stars, each with thousands of pieces of information in hundreds of tables) and using various selection methods narrowed the sample down to ~16,000 DA white dwarf stars. Further to this, after cross-matching the sample with the near-IR survey; UKIDSS, I produced a catalogue of a few hundred white dwarfs with an infrared excess. This is indicative of either a sub-stellar companion to the white dwarf or a debris disk. Debris disks are believed to be formed from the remnants of a planetary system around the white dwarf being disrupted by the extreme gravity of the white dwarf. Seeing as the Sun will eventually become a white dwarf, these white dwarfs with debris disks are the future of our solar system.
Publications I have been involved with:
- 2012MNRAS.425.1013G
: The unseen population of F- to K-type companions to hot subdwarf stars; Girven et al. (2012) - 2012ApJ...749..154G : Constraints on the Lifetimes of Disks Resulting from Tidally Destroyed Rocky Planetary Bodies; Girven et al. (2012)
- 2012MNRAS.421.1635F : A trio of metal-rich dust and gas discs found orbiting candidate white dwarfs with K-band excess; Farihi et al. (2012)
- 2011MNRAS.417.1210G : DA white dwarfs in Sloan Digital Sky Survey Data Release 7 and a search for infrared excess emission; Girven et al. (2011)
- 2011A&A...530A.114K : Cool DZ white dwarfs in the SDSS; Koester et al. (2011)
- 2011MNRAS.413.1121R : Post-common envelope binaries from SDSS-X: the origin of low-mass white dwarfs; Rebassa-Mansergas et al. (2011)
- 2011ApJ...728L...8F : Possible Signs of Water and Differentiation in a Rocky Exoplanetary Body; Farihi et al. (2011)
- 2010MNRAS.404..159G : PG1258+593 and its common proper motion magnetic white dwarf counterpart; Girven et al. (2010)
- 2010Sci...327..188G : Two White Dwarfs with Oxygen-Rich Atmospheres; Gänsicke, B. T.; Koester, D.; Girven, J.; Marsh, T. R.; Steeghs, D. (2010)
For a full list see: SAO/NASA Astrophysics Data System (ADS)
Write to:
Jonathan Girven,